Somatic hybridization between Lycopersicon peruvianum and L. pennellii: Regenerating ability and antibiotic resistance as selection systems

Abstract

Somatic hybrids were obtained between the reproductively-isolated tomato species Lycopersicon peruvianum and L. pennellii. Leaf protoplasts of the former species and protoplasts from cell suspension cultures of the latter were fused with polyethylene glycol. A double selection scheme for fusion products was used on the basis of regeneration ability in L. peruvianum and resistance to the antibiotic G418 (2-deoxystreptamine) in an L. pennellii cell line. One tetraploid and four hexaploid hybrids were obtained from this fusion. The hexaploids might have originated by fusion of two L. pennellii protoplasts and one L. peruvianum protoplast. The hybrids were identified on the basis of isozymes (loci Prx-1, Prx-2, Prx-4, Prx-6, Prx-7, Pgi-1 and putative locus Mdh-1), leaf, flower morphology and epidermal hairs. The expression of antibiotic resistance and regeneration ability in the hybrids indicate that these are dominant or codominant traits. The sterility and subvitality of the resulting hybrids questions the value of somatic hybridization as a useful breeding approach in Lycopersicon.